You guys have essentially hijacked this thread for your own little sword fight. Why don't you take this argument offline and hash it out amongst yourselves so that we don't have to read though 52 pages of opinion, speculation and anecdotes to find something marginally relevant to the average Tivo user impacted by SDV?

Why don't you use the little scroll wheel on your mouse and read the following threads with SDV adaptor progress in their title??:

I don't know what else to say but SA recently launched SDV and Mot is only still in trials with SDV yet they both had VOD for many years. I guess you just have a different definition of what SDV is and both Mot and SA must have launched your version of SDV years ago.

My original point is that the term SDV has been coopted to mean specifically using digital video switching to provide access to entire scheduled video services (like, "The Food Network HD" and "The History Channel HD")--it does not refer to the use of switching to provide VOD or IPPV. The fact that UDCR devices can't access those interactive services is well known and no one who bought one had the expectation of being able to use them without a leased STB (well, maybe a few slow-on-the-uptake people did ). No one cares about that--they care that their cable providers are using a new application of digital video switching to add new video services to tiers that they already subscribe to which they can't access using their UDCR equipment.

The title of this thread is "SDV FAQ". The FAQ in the top post does not refer to VOD or IPPV when it uses the term SDV. I defy you to find a single article posted in the online technical press in the past two years which uses any of the terms "Switched Digital Video", "Switched Digital", "Switched Video" or "Switched Video Broadcast" while referring to VOD or IPPV. Are we to read the headline, "NCTA and TiVo Announce Switched Digital Solution for HD DVRs", in the NCTA's press-releases to mean that they've developed a solution which gives HD DVRs access to VOD or IPPV? No. When we read that, there was no confusion--we all knew exactly what they were talking about.

Please--if there's a specific term for this recent bandwidth-conserving use of digital video switching on cable systems, please name it. Otherwise, we're left with having to say "non-VOD, non-IPPV SDV"; kind of awkward. Words and phrases which meant one general thing get coopted to mean something more specific all the time--language evolves, technical and otherwise, and like it or not, that's what's happened. We already had precise terms for VOD and IPPV; if we cut them out of the meaning of SDV, there's no loss to the jargon. Only the staunchly pedantic will mourn.

The problem has been that a few people insist on using SDV interchangeably with VOD in this thread. It always causes confusion and one has to believe that the people who use it that way are purposely trying to cause confusion, for whatever personal reason.

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Mike Scott

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Well, there was this whole ridiculous discussion, as a case in point. MichaelK states that "Howard Stern TV" is a VOD channel now, but might become an SDV channel in the future. lrhorer quips in with "Virtually no one offers VOD unless it's SDV." He knew exactly what MichaelK meant, but the pedant in him just couldn't resist making the useless point that all VOD is Switched Video. Yes, cable systems have been doing digital video switching for years, but they have not had the ability to do this switching-used-to-share-bandwidth-between-broadcast-services trick until recently, and it required the deployment of both new equipment and new software to acheive it.

BigBand Networks is probably the most popular supplier of systems for adding Switched Digital Video to cable networks. They have a product page at their site for "Switched Video" (here) which splits out into two sections, one labelled "Switched Digital Video" and one labelled "Video On Demand". Yes, VOD is "Switched Video" and yes, it's "Digital", but even the people who manufacture hardware and software systems for implementing it draw a distinction between "Video On Demand" and "Switched Digital Video".

The term "switched digital video" describes the types of services in cable networks that are a hybrid between VOD and traditional one-way broadcast services. VOD switches a singlecast interactive program to a user. SDV switches broadcast video streams, making each stream available to one or more subscribers who simply join the broadcast stream just as they would with normal broadcast services.

To the subscriber, SDV services are indistinguishable from traditional broadcast services.

(Forgive any typos--it's a "locked" PDF file that doesn't allow the cut operation so I had to transcribe that).

The cable technology industry has a clear definition of "Switched Digital Video" as used in their published literature and does not use it as an umbrella term which encompasses "Video On Demand". (That Moto whitepaper would suggest, rather than VOD being a type of SDV, that SDV is a type of VOD). SDV refers specifically to the use of video switching to share a pool of bandwidth on network edge segments between a group of broadcast video services. This is not a "misuse"--it's the firmly established meaning of the term. Arguing that "VOD" is a type of "SDV" is tedious, wrong (according to the cable equipment industry) and utterly unproductive.

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Mike Scott

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MichaelK states that "Howard Stern TV" is a VOD channel now, but might become an SDV channel in the future. lrhorer quips in with "Virtually no one offers VOD unless it's SDV." He knew exactly what MichaelK meant, but the pedant in him just couldn't resist making the useless point that all VOD is Switched Video.

That wasn't the thing that you and ah30k were complaining about. The complaint was that VOD was being used interchangeably with SDV, etc. WTF is the problem? Someone's being educated against their will?

Quote:

Yes, VOD is "Switched Video" and yes, it's "Digital", but even the people who manufacture hardware and software systems for implementing it draw a distinction between "Video On Demand" and "Switched Digital Video".

Of course they do. Good lord, why wouldn't they? They're two separate things. One is a mechanism, a protocol, while the other is one of the services made possible and available by that mechanism. In fact, the problem actually seems to stem from using the mechanism acronym (SDV) to also refer to another "service" (that is, something probably better called "Channel On Demand") made available by the mechanism.

Quote:

Arguing that "VOD" is a type of "SDV" is tedious, wrong (according to the cable equipment industry) and utterly unproductive.

Well it certainly is wrong, as VOD is certainly not a type of SDV, nor is SDV a type of VOD, and I don't think anyone has claimed that.

That wasn't the thing that you and ah30k were complaining about. The complaint was that VOD was being used interchangeably with SDV, etc. WTF is the problem? Someone's being educated against their will?

How is...

Quote:

Originally Posted by lrhorer

Virtually no one offers VOD unless it's SDV.

...not something which equates the two acronyms? Perhaps it's not using the two things "interchangeably"--I withdraw that claim. Happy now ? The statement does imply that VOD is a subclass of SDV, which, as the industry which invented both technologies defines the term SDV, is incorrect.

Quote:

Originally Posted by Firekite

Of course they do. Good lord, why wouldn't they? They're two separate things. One is a mechanism, a protocol, while the other is one of the services made possible and available by that mechanism. In fact, the problem actually seems to stem from using the mechanism acronym (SDV) to also refer to another "service" (that is, something probably better called "Channel On Demand") made available by the mechanism.

The industry does not "also" use the term SDV to refer to what you call "a service", the industry only uses the term to refer to that. In fact, I consider your claim that anyone (other than you and lrhorer) uses the term "SDV" to refer to a generic video switching mechanism used to implement "VOD" and other things to be nonsense until you show me some evidence otherwise, anywhere on a cable equipment OEM's website or in the technical press. I showed you some evidence supporting my claim that it only refers to "a service", including a succinct definition comparing the two given in a Motorola whitepaper; I could show you much more of the same.

Quote:

Originally Posted by Firekite

Well it certainly is wrong, as VOD is certainly not a type of SDV, nor is SDV a type of VOD, and I don't think anyone has claimed that.

Your statement...

Quote:

Originally Posted by Firekite

Switched Digital Video makes Video On Demand possible.

...sounds a whole lot like that, to me. What the people who created both VOD and SDV mean when they say "Switched Digital Video" (and again, the only thing that they mean when they say that) doesn't have anything to do with Video On Demand. To implement what they call "Switched Digital Video", you have to purchase a bunch of additional software and hardware. If you installed all of that stuff and later decided to remove it all, your network wouldn't be capable of what the cable industry calls "Switched Digital Video" anymore, but it would still be able to do VOD (if it were able to do it to begin with).

As I've shown, when Motorola, Cisco/SA and BigBand Networks say "SDV" they mean "video switching used to share a pool of bandwidth on edge segments between a group of broadcast video services"--if you examine the entirety of all of those companies' websites you will not find "SDV" used to mean anything else. It's a hot buzzword for a watershed technology which is being sold as a means for cable to continue to compete with the plethora of high definition broadcast services being offered by their DBS and telecomm rivals, without expending the momumental amounts of cash and time that would be required to actually expand the real bandwidth capacity of their networks. Arguing that it's a generic term for the basic video switching mechanism used to implement it and VOD is specious.

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Mike Scott

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Holy buttnuggets. It's like trying to convince relatives that I'm sending them an email, not an internet, that the email is transmitted over the internet, and they're insisting that because Sen. Ted Stevens said so, the facts themselves are irrelevant.

Holy buttnuggets. It's like trying to convince relatives that I'm sending them an email, not an internet, that the email is transmitted over the internet, and they're insisting that because Sen. Ted Stevens said so, the facts themselves are irrelevant.

Yeah, it's a whole lot like that, isn't it ? (And thanks for that colorful interjection, BTW). The difference is that Sen. Stevens is pretty far removed from the details of Internet technology (though he may serve on some related advisory boards); the examples I offer are from companies who are at the heart of cable network tech. I give you examples of the industry's use of the term "Switched Digital Video" as drawn from three major OEMs providing equipment and software for implementing "Switched Digital Video" in HFC cable television networks. You offer as conflicting "fact" merely your sayso. Forgive me if your "argument" fails to impress.

VOD switches a singlecast interactive program to a user. SDV switches broadcast video streams, making each stream available to one or more subscribers who simply join the broadcast stream just as they would with normal broadcast services.

(I think that Motorola is a somewhat stronger authority on cable network technologies than Sen. Stevens is an expert on the nuts and bolts of the Internet--YMMV ). Whose definition of SDV should we use? One from Firekite (and lrhorer) or one from Motorola? I think that I've made it clear which way I lean on that.

All we're really asking is to be able to continue this discussion with people being able to refer to "SDV channels" and "VOD channels" in the same post without someone replying "but VOD channels are SDV channels", which is, according to Motorola's definition of SDV--and BigBand's and Cisco/SA's--wrong, your personal definition of SDV notwithstanding, whereever it is that you derive it from.

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Mike Scott

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the examples I offer are from companies who are at the heart of cable network tech.

No, the examples you offer are from the marketing departments of companies who are involved in cable network tech. And honestly, I don't have a problem using that naming convention if that's where we're going with it. I do have a problem with insisting that one has nothing to do with each other and refusing to acknowledge the technical reality.

Quote:

All we're really asking is to be able to continue this discussion with people being able to refer to "SDV channels" and "VOD channels" in the same post without someone replying "but VOD channels are SDV channels"

I'm fine with that, but that's the first time in recent memory that such an objection's been made. That wasn't your point before, remember?

SDV does less, actually, it just chooses/releases an existing linear stream, VOD, in addition to that, can choose a dynamic stream from a menu, and manipulate (trick-play) it, the latter which cannot (at least yet, or the cable providers don't want) over the TA interface.

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No, the examples you offer are from the marketing departments of companies who are involved in cable network tech. And honestly, I don't have a problem using that naming convention if that's where we're going with it. I do have a problem with insisting that one has nothing to do with each other and refusing to acknowledge the technical reality.

The marketing departments get most of what they say from the engineers (many of the marketers at such companies have undergrad engineering degrees). I'm a retired software engineer who worked for over 30 years on firmware in the computer storage, large-scale networking equipment and consumer electronics industries, and I've been engineering laison to marketing a few time (I actually worked for Moto for a while, but not on broadband). I assure you that engineers and lawyers went over every word of that whitepaper . The choice of "Switched Digital Video" as the label for the "sharing a pool of bandwidth on a edge segment between many broadcast streams" technology was probably mostly on marketing, though. It doesn't matter--the term was coopted to mean specifically that and the industry is consistently sticking to it. When you see "Switched Digital Video" or "SDV" in the related technical press or on sites like Answer.com and Wikipedia, everybody's talking about the same thing. The FAQ at the top of this thread is specifically about that technology and we as CableCARD TiVo owners (except that you aren't one, are you?) are specifically concerned with that technology and how it's shutting us out of new cable content that we had every expectation of being able to get. Posting objections of "VOD channels are SDV channels" does nothing to aid the discussion and merely creates massive ratholes like the one that we're in now.

Sure VOD and SDV are related--they're both based on video switching, but both are much more than that. SDV, as the term is defined by the industry, is not a component of VOD.

Quote:

I'm fine with that, but that's the first time in recent memory that such an objection's been made. That wasn't your point before, remember?

I'm sorry, but I don't recall stating any other objection than to people sayng things that implied that SDV is part of VOD (confusing other people into thinking that they were saying that VOD is a kind of SDV, leading to 20-post arguments). If I stated it poorly somewhere, I apologize.

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Mike Scott

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Well, there was this whole ridiculous discussion, as a case in point. MichaelK states that "Howard Stern TV" is a VOD channel now, but might become an SDV channel in the future. lrhorer quips in with "Virtually no one offers VOD unless it's SDV." He knew exactly what MichaelK meant

As anyone who reads the link you posted can see, MichaelK did not say what you claim he did, and I did not say what you claim I did. As to my knowing what MichaelK meant, in a forum such as this, I cannot assume anyone means anything other than precisely what they say, because to do so is to assume others reading the very same post have the proper background to read the same things between the lines that I might have. In this particular case, however, it seemed likely the poster was making a distinction between the equipment which carries broadcast SDV and VOD. There is none such. If you are claiming he meant Howard Stern TV might be changing from purely on-demand programming to purely or partially scheduled programming, then the fact is I didn't follow at all what you claim the OP had in mind. Either way, your assertion that I "knew exactly what MichaelK meant" and it's negative connotations were inappropriate to my post.

Many people on this forum seem to think there is some fundamental difference between SDV and VOD as it relates to the transmission standards. There is not. Many people are advocating eliminating SDV because they think SDV and VOD are independant technologies, and eliminating SDV would not eliminate VOD. In the context of a CATV system, they are not, and it would. Specifically, there are three and only three widely deployed digital video systems: linear, SDV, and IPTV. VOD uses precisely the same transmission equipment, reception equipment, and interactive protocols as that used by switched scheduled broadcasting, whatever the underlying protocol. It does require an additional set of protocols to allow the user to initiate the stream, as well as a vastly greater bandwidth from the servers. Scheduled programs allow no such control by the user, but the modulators, receivers, and streams are all identical. Indeed, while a linear QAM can distribute nothing but linear video, an SDV QAM can readily be transmitting a mixture of scheduled programs and VOD or similar programming, and that mixture can change at any moment. Looking at a particular timeslot within an SDV QAM, one moment it can be carrying a scheduled program, and the very next moment it may suddenly rewind by 30 seconds. A minute or two later it might start transmitting one of HBO's VOD offerings.

The video protocols are somewhat similar to data networking. Many networks switch at Layer 2, that being most often Ethernet these days, but some systems still employ Token Ring or SONET based transport streams (SONET or TDM transports still being the main choce for WAN connections). Some, however, switch at Layer 3. The Layer 2 networking is roughly analogous to CATV or FIOS, and SDV switching is more or less analogous to Layer 3 switching, while IPTV is IP based and can switch at Layer 2, Layer 3, or both.

The most common Layer 3 protocol these days is IP, although again there are others such as IPX, ISIS, etc. Similarly, the CATV provider can choose to implement SDV or IPTV or whatever other switched transport technology they may choose. There is nothing in the transport systems which prevent CATV systems from employing something other than SDV, but no matter what system they choose, no UDCP (by itself) can effectively receive program content delivered over the system of choice. By a very wide margin, SDV is the choice for most CATV providers, so in practical terms if we are talking about a switched service on a CATV system, we're talking SDV.

The two most common layer 4 protocols are UDP and TCP. Neither one requires IP to be the networking layer: they both can quite happily transverse an IPX or ISIS network, but speaking a bit loosely they both require there to be a Layer 3 protocol to carry them. Again, similarly, VOD doesn't necessarily require SDV for its transport. It's quite easy to implement it over IPTV. It's even hypothetically possible to implement it entirely over linear QAMs, provided the CATV company doesn't mind eating up its entire 750-1000MHz network with only 3 or 4 channels. No one, however, is that phenomenally stupid, so speaking in real world terms, VOD on a CATV system requires SDV.

Quote:

Originally Posted by mikeyts

but the pedant in him just couldn't resist making the useless point that all VOD is Switched Video.

It is not a useless point. No UDCP (by itself) can receive VOD. There are two reasons this is the case. One is regulatory and not absolute. To wit, the CATV providers are not bound by law to provide VOD and other 2-way services to UDCPs, no matter how they are modified. Thus, even with the TA, most users won't get VOD, video rewind, internet browsing, online banking, interactive gaming, etc.

The second is physical. If the unit cannot receive SDV programs, it can't receive VOD. If TiVo, the CATV companies, and the CATV equipment manufacturers chose to (agreed to), the TA could readily provide VOD and the other non-scheduled 2-way services. Why? Because it is all 100% SDV, especially as far as the STB / DVR is concerned. It only requires extra software to handle VOD, not any different hardware.

Quote:

Originally Posted by mikeyts

BigBand Networks is probably the most popular supplier of systems for adding Switched Digital Video to cable networks.

No doubt, although I haven't seen the actual numbers. It is TWC's choice.

Quote:

Originally Posted by mikeyts

They have a product page at their site for "Switched Video" (here) which splits out into two sections, one labelled "Switched Digital Video" and one labelled "Video On Demand".

Which is no big surprise. VOD requires a huge amount of processing and switching power and an unbelievable amount of server bandwidth, while plain vanilla scheduled SDV requires comparatively little. Using a different analogy, SD video requires much less horsepower than HD video, and a system capable of handling SD video won't necessarily be able to handle HD video. The fact it requires more capable transmitters and receivers doesn't mean HD isn't video. Similarly, the fact VOD can easily eat up hundreds of times the server horsepower and requires additional protocols doesn't mean it isn't SDV in the CATV environment. More to the point, if the video provider in question uses some other switching protocol (can you say FIOS or IPTV?), then for that system the VOD is not SDV. The number of fiber / aluminum based CATV providers who aren't using SDV for switching is tiny, however. To put it more simply, if a CATV system deploys VOD, then they have SDV capability in place. Deploying only basic SDV capability doesn't allow them to deploy VOD, however.

Quote:

Originally Posted by mikeyts

I've examined some product literature at Cisco and Motorola as well--it's riddled with phrases like "enable QAM sharing between SDV and VOD services"

Which wouldn't be possible if they didn't use the same switching protocol. It's called SDV. I never said the two terms were anything like synonyms. I also never said they were fundamentally inseparable. What I did say is that if it's VOD on a CATV system, it's SDV (with an insignificantly small number of exceptions for those using some switched protocol other than SDV).

Quote:

Originally Posted by mikeyts

SDV refers specifically to the use of video switching to share a pool of bandwidth on network edge segments between a group of broadcast video services.

Which is PRECISELY what VOD is... and video rewind... and video internet browsing... and On Demand PPV... and interactive gaming... and video conferencing... and of course scheduled SDV broadcasts.

Quote:

Originally Posted by mikeyts

This is not a "misuse"--it's the firmly established meaning of the term.

... and it applies perfectly to VOD. Nothing in that definition limits the bandwidth of the service, requires any of the services to be authorized for multiple viewers, requires any of the services to be limited to a particular schedule, or requires any of the services to be restricted from initiation by one of the edge segments. Logically, the only difference between VOD and "ordinary" SDV is the video stream at the server is initiated by a user if it is VOD and by an automated system (often a network feed) if it is scheduled programming. Physicaly the difference is that a single scheduled feed only requires one continuous data stream coming from the server, while a VOD service can require hundreds or perhaps even thousands of intermitytent streams.

Quote:

Originally Posted by mikeyts

Arguing that "VOD" is a type of "SDV" is tedious, wrong (according to the cable equipment industry) and utterly unproductive.

I'll let all my friends and former colleagues who are still video engineers in the CATV industry know they are wrong according to themselves. As far as "unproductive" is concerned, the number of posts above which suggest some of the readers think VOD could be deployed in a CATV system without deploying SDV (or some other switched system which would be just as incompatible with the TiVo) is quite significant, and I do not consider any post which seeks to correct such misaprehensions to be unproductive. If you find them so, the skip them. No one is forcing you to read my posts. Indeed, I consider any attempt to fundamentally differentiate the issues with VOD and SDV in the context of the TiVo or understanding how either works to be counterproductive.

SDV does less, actually, it just chooses/releases an existing linear stream, VOD, in addition to that, can choose a dynamic stream from a menu, and manipulate (trick-play) it, the latter which cannot (at least yet, or the cable providers don't want) over the TA interface.

Well, not just VOD, but all on-demand and interactive services other than regularly scheduled SDV programming. In terms of the number of streams and amount of bandwidth used, many CATV systems employ a great deal more in services other than VOD and scheduled programming (both linear and switched) put together.

You are claiming I cannot say I have a dog because she is an Irish Wolfhound. Well, almost. Where this analogy breaks down is that not all VOD is SDV, but in all but a very tiny number of CATV systems, it is. I can't think of any Irish Wolfhounds anywhere who aren't dogs, my dog's belief she is human notwithstanding.

Let's put it this way. If some of the people in this forum and elsewhere had their way and the FCC forced every CATV system to rip out their SDV equipment, what would happen to VOD on those systems?

Answer: it would stop dead cold, because the equipment and protocols which deliver SDV are the same ones which deliver VOD. VOD requires additional equipment at the TOC, to be sure, and the switches must have much greater throughput. You can insist that "VOD isn't SDV" all you want, but it uses the same streams as SDV, the same modulators as SDV, the same receivers SDV, has precisely the same engineering problems with UDCPs that SDV does, requires the same upgrades SDV does (yes, plus some additional ones), and produces an output which is completely indistinguishable from SDV. Oh, and by the way, what does a CATV company have to purchase, install, and maintain after implementing a VOD system - including STBs and DVRs - in order to deliver SDV? Nothing whatsoever. But VOD and SDV are completely separate and must be considered to be unrelated? OoohhhKaaaayyyy.....

Quote:

Originally Posted by mikeyts

The statement does imply that VOD is a subclass of SDV

No, it doesn't. It does imply any CATV system which offers VOD has SDV, which is accurate although not quite 100% true. There are a small handful of exceptions.

Quote:

Originally Posted by mikeyts

In fact, I consider your claim that anyone (other than you and lrhorer) uses the term "SDV" to refer to a generic video switching mechanism used to implement "VOD" and other things to be

I never said that was the case. SDV is what is used by virtually all CATV systems to deliver VOD. FIOS uses IPTV. In the early days when we were working on the Pegasus project (and I was working for Time Warner Cable) we tried a number of switching systems to deploy VOD in the lab. I have no doubt there are still some small CATV systems out there using proprietary switching protocols to deliver VOD. I know for a fact some have tried IPTV, but I don't know if any fiber and aluminum providers are still toying with IPTV or not.

Quote:

Originally Posted by mikeyts

To implement what they call "Switched Digital Video", you have to purchase a bunch of additional software and hardware.

No, you don't, which is the point you seem to be missing completely. Scheduled video only requires an input stream to the server, which can be almost pathetically puny. VOD requires the server to originate the streams and requires them to originate potentially thousands of streams. All the scheduled video sever really needs to do is encrypt the incoming stream and pass it on, assuming it's encrypted. If it's a local broadcast stream, it doesn't even do that.

Quote:

Originally Posted by mikeyts

If you installed all of that stuff and later decided to remove it all, your network wouldn't be capable of what the cable industry calls "Switched Digital Video" anymore, but it would still be able to do VOD (if it were able to do it to begin with).

No, it wouldn't, because all one would be left with is a bunch of hyper-powerful servers and switches with no way to get the signal to the user. I don't know where you got the notion VOD uses a separate set of video equioment from SDV, but it doesn't. Remove SDV from the CATV system and VOD is gone... kaput... blasted... it no worky. Now do you understand?

Quote:

Originally Posted by mikeyts

It's a hot buzzword for a watershed technology which is being sold as a means for cable to continue to compete with the plethora of high definition broadcast services being offered by their DBS and telecomm rivals, without expending the momumental amounts of cash and time that would be required to actually expand the real bandwidth capacity of their networks.

Which includes VOD and other on-demand services. Scheduled video services (linear and switched) may utilize in aggregate a few Gbps at the TOC. On demand sevices (including VOD) can easily require 100Gbps or more. There is more than one switching protocol which can be used to deliver on-demand services, but almost universally the one chosen by CATV providers is SDV. Now if you want to differentiate the service provided by scheduled SDV from the underlying protocol, then OK, but it is the exact same protocol used by SDV and requires all the same equipment and software used by SDV. We also need a name for it. What do you suggest? The only way to remove SDV capabilities from the system is to remove those protocols, in which case pffft! goes VOD, your assertion notwithstanding.

Quote:

Originally Posted by mikeyts

Arguing that it's a generic term for the basic video switching mechanism used to implement it and VOD is specious.

It's not a generic term. It refers specifically to the switching protocols used by almost every CATV system which deploys switching, so it's almost universal in CATV circles. There isn't a separate one for VOD and other interactive and on-demand services.

Here we have a fundamental difference of opinion. I (and I believe many others) use the term "SDV" to refer only to the switching of scheduled broadcast non-trick-play services as demonstrated by the recent releases from SA, Mot and Bigband.

Obviously. From an engineering standpoint it is a mostly superfluous distinction, especially from the standpoint of the customer's receiver (in this forum, a TiVo). It can be a significant distinction, however, in light of the FCC regulations on what must and must not be supported on UDCPs. If the distinction is made, however, then it also must be made between the services implied by the term "SDV" and the underlying protocols, since those same protocols are used by on-demand services, including VOD. This is not being done (or apparently understood) in this thread. Certainly, it's not unheard of for a single term to refer to both a service and it's underlying protocols.

Quote:

Originally Posted by ah30k

Dynamic services like VOD are unique to the home ordering it and involve so many other technologies such as trick-play controls that they are refered to in other terms such as "VOD".

True. It also, however, relies on an underlying switching protocol set, or rather it must in all practicality do so. It generates far too much bandwidth to be practical on a linear system. For almost all CATV systems that underlying protocol is SDV, or if you insist the same protocol set used by SDV.

Quote:

Originally Posted by ah30k

VOD has been around much longer than the SDV as

Indeed it has. I never suggested it hadn't. Since my personal familiarity with VOD extends back into the early 1990s, it would be singularly odd should I do so.

Quote:

Originally Posted by ah30k

I've described and the use of the term SDV when you mean VOD is just plain confusing.

I have never done so, or at least not intentionally. The fact I expounded the deduction that (virtually) any CATV system which offers VOD is employing SDV in no way confuses the two. When I say "VOD" I mean the service which allows consumers to select a program from a menu and start playing it on their TV from the headend. When I say "VOD and similar services" I mean anything which employs the VOD protocols to deliver a user controlled video from the headend. When I say "SDV" I mean the protocols used by the vast majority of CATV systems who deploy switching at all which allow a different set of digital streams to be delivered to each independent edge network. Unless I specifically limit the use of those protocols to scheduled programs, the term is intended to include on-demand services.

Quote:

Originally Posted by ah30k

I'd bet a case of your favorite beverage that you are the only person on this forum using the term SDV to refer to VOD services.

I don't, but I do use it to include VOD and other on-demand and interactive services. What term would you prefer I use to include all services which employ the digital video switching protocol set also used by scheduled SDV? I suggest you make it a good one, because I rarely have any reason to limit the discussion to scheduled programs, especially since they are a tiny minority.

Under the best of circumstances, engineering estimates made as far ahead as that one was are of limited accuracy. Being an estimate of a cooperative effort by CableLabs, Motorola, Scientific Atlanta, TiVo and all of the major cable providers, this one had almost no chance of being precise. Still, I don't think that it will be more than 2 or 3 months late, which is pretty good, considering.

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Mike Scott

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Interesting... Now if non-CableCard Tivo users are also able to get hold of one for free this may just be the perfect solution to the Tivo no guide for unencrypted QAM channels issue (since the tuning adapter should provide the channel mapping function).

I feel fairly certain that TiVo's going to have to work that out themselves. Not being able to get a potential boatload of new conditional access channels is one thing (and in some places, like Hawaii, a bunch of old ones); not being able to figure out where the non-conditional access ones are is another and most definitely not the cable industry's problem. I have to think that only people attaching them to certain certified pieces of equipment in which one or more leased CableCARDs is installed will ever get one of these things.

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Mike Scott

"To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts." -- hookbill

So far, I have to applaud Cox for selecting channels with limited appeal, and none that are HD. Of course, I know that's the whole idea behind SDV (moving limited appeal channels to it, and leaving the rest alone), but there were rumours that in the Phoenix market the plan was to put everything digital on SDV.

In my case so far, I see no need to get a tuning adapter, even if it is free. I either don't subscribe to most of these channels, or in the exceptionally rare case I need to record something from one I can use my S2 that is still hooked up to a cable box.

You guys in phoenix are lucky. In San Antonio all the good stuff is SDV. Give them time, they'll screw you eventually. I can't wait for the adapter. Tired of having to go into my office to see all the channels.